Answer: How to check a not-defined variable in JavaScript

answer re: How to check a not-defined variable in JavaScript

May 13 '09

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The only way to truly test if a variable is undefined is to do the following. Remember, undefined is an object in JavaScript.

if (typeof someVar === 'undefined') {
  // Your variable is undefined
}

Some of the other solutions in this thread will lead you to believe a variable…

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